diff --git a/compiler/optimize-il.rkt b/compiler/optimize-il.rkt
index e41988e..f89ecea 100644
--- a/compiler/optimize-il.rkt
+++ b/compiler/optimize-il.rkt
@@ -54,6 +54,7 @@
           (define goto-target (GotoStatement-target next-stmt))
           (cond
             [(Label? goto-target)
+             (log-debug (format "merging label ~a and ~a" last-stmt (Label-name goto-target)))
              (ufind:union-set a-forest last-stmt (Label-name goto-target))
              (loop (rest stmts) next-stmt)]
             [else
diff --git a/js-assembler/assemble.rkt b/js-assembler/assemble.rkt
index 9ea956d..7dcf542 100644
--- a/js-assembler/assemble.rkt
+++ b/js-assembler/assemble.rkt
@@ -179,19 +179,25 @@ EOF
 };"
           (assemble-label (make-Label (BasicBlock-name a-basic-block)))
           (assemble-label (make-Label (BasicBlock-name a-basic-block)))
-          (string-join (assemble-block-statements (BasicBlock-stmts a-basic-block)
+          (string-join (assemble-block-statements (BasicBlock-name a-basic-block)
+                                                  (BasicBlock-stmts a-basic-block)
                                                   blockht
                                                   entry-points)
                        "\n")))
 
 
-(: assemble-block-statements ((Listof UnlabeledStatement) Blockht (Setof Symbol) -> (Listof String)))
-(define (assemble-block-statements stmts blockht entry-points)
+(: assemble-block-statements (Symbol (Listof UnlabeledStatement) Blockht (Setof Symbol) -> (Listof String)))
+(define (assemble-block-statements name stmts blockht entry-points)
   
   (: default (UnlabeledStatement -> (Listof String)))
   (define (default stmt)
+    (when (and (empty? (rest stmts))
+               (not (GotoStatement? stmt)))
+      (log-debug (format "Last statement of the block ~a is not a goto" name)))
+
     (cons (assemble-statement stmt)
-          (assemble-block-statements (rest stmts) 
+          (assemble-block-statements name
+                                     (rest stmts) 
                                      blockht
                                      entry-points)))
   
@@ -244,12 +250,14 @@ EOF
                      [(set-contains? entry-points (TestAndJumpStatement-label stmt))
                       (list (assemble-jump (make-Label (TestAndJumpStatement-label stmt))))]
                      [else
-                      (assemble-block-statements (BasicBlock-stmts 
+                      (assemble-block-statements (BasicBlock-name
+                                                  (hash-ref blockht (TestAndJumpStatement-label stmt)))
+                                                 (BasicBlock-stmts 
                                                   (hash-ref blockht (TestAndJumpStatement-label stmt)))
                                                  blockht
                                                  entry-points)])
                  "} else {"
-                 ,@(assemble-block-statements (rest stmts) blockht entry-points)
+                 ,@(assemble-block-statements name (rest stmts) blockht entry-points)
                  "}")]
            
            [(GotoStatement? stmt)
@@ -261,7 +269,9 @@ EOF
                     (default stmt)]
                    [else
                     (log-debug (format "Assembling inlined jump into ~a" (Label-name target)) )
-                    (assemble-block-statements (BasicBlock-stmts
+                    (assemble-block-statements (BasicBlock-name
+                                                (hash-ref blockht (Label-name target)))
+                                               (BasicBlock-stmts
                                                 (hash-ref blockht (Label-name target)))
                                                blockht
                                                entry-points)])]
diff --git a/js-assembler/runtime-src/baselib-modules.js b/js-assembler/runtime-src/baselib-modules.js
index 40c2612..ee98f15 100644
--- a/js-assembler/runtime-src/baselib-modules.js
+++ b/js-assembler/runtime-src/baselib-modules.js
@@ -53,7 +53,10 @@
         var oldErrorHandler = MACHINE.params['currentErrorHandler'];
         var afterGoodInvoke = function (MACHINE) { 
             MACHINE.params['currentErrorHandler'] = oldErrorHandler;
-            succ();
+            if (isInternal) { succ(); }
+            else {
+                throw new plt.runtime.HaltError(succ)
+            }
         };
 
         if (this.isInvoked) {
diff --git a/js-assembler/runtime-src/runtime.js b/js-assembler/runtime-src/runtime.js
index b9ef11b..ee7f914 100644
--- a/js-assembler/runtime-src/runtime.js
+++ b/js-assembler/runtime-src/runtime.js
@@ -562,7 +562,7 @@
 
     // Executes all programs that have been labeled as a main module
     var invokeMains = function(machine, succ, fail) {
-        runtime.ready(function() {
+        runtime.ready(function invokeMain() {
             setReadyFalse();
             machine = machine || runtime.currentMachine;
             succ = succ || function() {};